Assessment of Magnetic Techniques for Understanding Complex Mixtures of Magnetite and Hematite: The Inuyama Red Chert
Assessment of Magnetic Techniques for Understanding Complex Mixtures of Magnetite and Hematite: The Inuyama Red Chert
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DOI：
10.1029/2020jb019518
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发表时间：
2020-12
期刊：
影响因子：
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通讯作者：
P. Hu;H. Oda;Xiang Zhao;R. Harrison;D. Heslop;Tetsuro Sato;A. Muxworthy;A. Roberts
中科院分区：
文献类型：
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作者：
P. Hu;H. Oda;Xiang Zhao;R. Harrison;D. Heslop;Tetsuro Sato;A. Muxworthy;A. Roberts
磁铁矿和赤铁矿混合物广泛存在于自然界中。这些矿物记录的信号的磁分解对于评估其各自古地磁剩磁的起源以及提取地质和古环境信息非常重要。然而，由于赤铁矿的弱磁化和高磁化率，复杂磁铁矿和赤铁矿混合物的磁信号分离是困难的。我们在这里评估的相对有效性的一阶反转曲线（FORC）和扩展的FORC-型图，FORC-主成分分析（PCA），等温剩磁磁化（REMITRAGE）曲线分解，和PCA的剩磁滞后曲线从磁性复杂的日本犬山红燧石样品中分离磁性成分。我们还进一步表征了磁区状态和磁区分布的磁铁矿和赤铁矿与FORC-PCA和磁区采集分析在红色燧石。我们表明，曲线分解可以提供与磁化率相关的有价值的组件特定信息，而FORC-PCA可以实现有效的磁畴状态识别。剩余磁滞回曲线的主成分分析提供了有关影响剩余磁变化和微妙矫顽磁力变化的最重要因素的有用信息。为了识别复杂的磁铁矿和赤铁矿混合物中的成分，我们建议结合代表性样品的FORC分析，以确定域状态和磁化率分布的Reynolds滞后曲线的PCA分析。
Magnetite and hematite mixtures occur widely in nature. Magnetic unmixing of the signals recorded by these minerals can be important for assessing the origin of their respective paleomagnetic remanences and for extracting geological and paleoenvironmental information. However, unmixing magnetic signals from complex magnetite and hematite mixtures is difficult because of the weak magnetization and high coercivity of hematite. We assess here the relative effectiveness of first‐order reversal curve (FORC) and extended FORC‐type diagrams, FORC‐principal component analysis (PCA), isothermal remanent magnetization (IRM) curve decomposition, and PCA of remanent hysteretic curves for unmixing magnetic components in samples from the magnetically complex Inuyama red chert, Japan. We also further characterize the domain state and coercivity distributions of both magnetite and hematite with FORC‐PCA and IRM acquisition analysis in the red chert. We show that IRM curve decomposition can provide valuable component‐specific information linked to coercivity, while FORC‐PCA enables effective magnetic domain state identification. PCA of remanent hysteretic curves provides useful information about the most significant factors influencing remanence variations and subtle coercivity changes. To identify components in complex magnetite and hematite mixtures, we recommend PCA analysis of remanent hysteretic curves combined with FORC analysis of representative samples to identify domain states and coercivity distributions.